Title : ( Fabrication, characterization, and measurement of some physicochemical )

ZnO nanofluids have been prepared by dispersing ZnO nanoparticles in the ethylene glycol (EG) and glycerol
(G) as the base fluids. Ammonium citrate, as a dispersant, has been used to improve the dispersion of
nanoparticles and suppressing formation of particle clusters to obtain stable suspensions.
The thermal conductivity of ZnO nanofluids has been measured as a function of the volume fraction and
temperature. The thermal conductivity of ZnO/EG and ZnO/G nanofluids increases nonlinearly up to
10.5% and 7.2%, respectively, as the volume fraction of nanoparticles increases up to 3 vol.%. The thermal
conductivity of a ZnO nanofluid increases nonlinearly with increasing the temperature at a constant volume
fraction of nanoparticles.
For the first time, we have measured the viscosity and surface tension of ZnO nanofluids. The viscosity
ratio of nanofluids increases with increasing concentration and decreasing the temperature. The surface
tension ratio of suspensions containing solid particles increases with increasing the volume fraction of
the solid nanoparticles.
The experimental data for thermal conductivity and viscosity have been compared with some existing
theoretical models.